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A Suspect says, ­I'll take a polygraph (lie detector) test."

The offer to take a polygraph examination is usually a stall tactic by the suspect. The suspect has little to loose by agreeing to take an examination since it is unlikely that an examiner will be available at the moment of his offer. If there is an examiner available, the suspect will then suggest that he should talk with someone before taking the examination. Either way, the suspect's goal is to postpone the interrogation or interview until some later time. At the agreed upon time, guess who fails to arrive? The suspect misses his appointment because he forgot, his (parents, friend, lawyer) told him not to take the examination or some other contrived reason.

Depending on the examiner's schedule, the suspect may have bought weeks or even months before being challenged about the incident again. With a little luck and a busy investigative schedule, he might even fall through the cracks and have this case buried under a mound of other work. The suspect has also inadvertently learned that the case against him is relatively weak and there may be some doubt about his guilt. The suspect recognizes if there was sufficient evidence to arrest or convict, why would there be an offer of a polygraph examination.

There are several possible responses to the suspect's offer to take an examination.

1)    All right that would be great. Here let me have you sign this polygraph consent form. (This reply is made with the presentation of a consent form for the suspect to sign indicating his willingness to take an examination.) The simple form consists of a couple of sentences authorizing a polygraph test. Since the suspect' offer to submit to the examination is being challenged, his behavior can be assessed by the interrogator. The guilty suspect will likely be reluctant to sign the document, or he will ask to think about it or consult with someone. The suspect has now further confirmed the interrogator's opinion that the he is involved in the incident. However, if the suspect signs the form without reluctance, asking when the test will be administered this may be an indication of truthfulness.

From an investigative standpoint it is unlikely that the suspect will appear for the examination when they delay signing the permission form. By scheduling the test, the interrogator has indirectly told the suspect there is doubt about his guilt. This then postpones the entire process in favor of the suspect and will probably increase his future resistance to a confession. Since it is unlikely that the suspect will appear for the polygraph examination, the interrogator might be advised to continue the interrogation using the following strategy.

2) I might at some point offer you a polygraph test, but I would want it to be one that you could pass. Based on the investigation, I know that you could not pass because you are involved in this situation. What I would rather do is to give you a test you could pass. Asking questions like, "Did you need the money for bills?" or "Did you plan this out?" so that the polygraph would show you are telling the truth and put a positive spin on this incident.

Using this response, the interrogator does several positive things for himself during the interrogation. First, he displays a confidence in the suspect's guilt, which further confirms the suspect's belief that he has been identified. Second, the interrogator presents the polygraph as an action capable of confirming the positive aspects of the suspect's involvement. The questions, such as "Did you plan this out?", are an extension of the rationalization the interrogator was using earlier in the conversation. Finally there is the benefit of time management in the investigation. The interrogator has set aside the time for the encounter and the suspect has presented himself so if it can be concluded during this single meeting with an obvious time savings.

3)    I don't even want to talk about that.? Legal Note relating to the polygraph. The Employee Polygraph Protection Act prohibits or restricts most forms of polygraph testing except under certain circumstances by private sector investigators. The private sector investigator should be aware of the legal pitfalls of this act before mentioning, discussing or suggesting the polygraph with the suspect. Public sector investigators may also be restricted by state law or collective bargaining agreements. Many states also have enacted victim rights legislation prohibiting or restricting the polygraph testing of victims. The investigators' awareness of the legal constrains will change the possible responses to the suspect.




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